Minimizing fire risk when operating rockets, gas-generators or the like



Sept. 4, 1956 s A MINIMIZING FIRE RISK WHEN OPERATING ROCKETS, GAS-GENERATORS OR THE Filed Aug. 12, 1953 2,761,282 LIKE 2 6 SPHKKIBENEM R l2 I4 GIY Tf/Z 29 I5 24 I7 23 n 45 FIGJ. I 25 50 4a 49 ll l'l'l'l'k ,wrmau I I Invcmfo'r SIDNEY A E N pYWv United States Patent" MINIMIZING FIRE RISK WHEN OPERATING ROCKETS, GAS-GENERATORS ORTHE Sidney Allen, Park Side, Coventry, England, assignorto ikr'rt'rllstrong Siddeley Motors'Limited, Coventry, Eng

Application August 12, 1953, SerialNo. 373,763"

Claims priority, application Great September 16, .1952

4Claims. (Cl. 60 39.09)

This invention relates to rocket motors, gas-generators or the like devices having chambers-in'which combustion ingredients are burned, and particularly to those which are installed on aircraft.

If for some untoward reason theoperating tempera ture in such a device should rise tosuch an extent that the'walls are likely to be burnedthrough, there is a risk igniting any surrounding structure, which may. cause disastrous results.

The main object of the invention isftopreventsueh fire hazardin an effective manner-and'to engender confidence in the personnel under whose control thedevice According to the invention, the exterior ofthe'device is enclosed by; a'fluid-tight jacket to which isfed a fluid ata' pressure higher than that obtaining.during'opera tion'within the device sothat, in'the eventofacornmunicatin'g aperture being established between the intei-ior of the device and thejacket' (by'burning-throu n'of the encompassing .wall'fof the device); the higher ressurein the jacket will restrain the flaming asesrrom passingoutwardly through the aperture, i. e., the flaming gases will'be constrained to move'in theirnormal direction to the normal outlet of th'e de'vice admixed with higher pressure fluid passing inwardly from the jacket.

Tho-invention further involves the' provision of -means for' cuttingjoif the supply off-combustion ingredients to the device, said means being responsive to a fall in the pressure of the fluid fed to the fluid-tight jacket.

Thus, the supply passage for the fluid in the jacket (which may be an inert gas such as nitrogen) may also communicate with a pressure-responsive switch adapted under the pressure to close an electric circuit for a solenoid-valve controlling means whereby a supply of combustion ingredients can be fed to the device. The drop in pressure, which is occasioned by any flow of the higherpressure fluid into the interior of the device, causes the pressure-responsive switch (biased to the open position) to be actuated to de-energize the solenoid-valve and so interrupt the supply of combustion ingredients to the device. To ensure that this would occur substantially simultaneously with the inflow of higher-pressure fluid into the device there may be provided an appropriate restriction in the supply passage upstream of the communication with the pressure-responsive switch.

In the accompanying drawings:

Figure 1 is a diagram, in sectional elevation, of a rocket motor and of control means therefore when adapted according to the invention; and

Figure 2 is a fragmentary view illustrating a modified form of the control means.

Like references are applied to both figures to denote corresponding parts.

Referring now to Figure l, 11 indicates a gas generator in the form of an evaporator chamber portion of the rocket motor, 12 the main fuel burner, which is downstream of the evaporator portion, and 13 the combustion chamber of the rocket motor. It will be understood in of fl'ame issuing from the resulting aperture and l 2 practice that the casing 14 will be surrounded by a jacket (omittedfor the sake of clearness) for a cooling-fluid (for example; the'mai n fuel supply for the rocket motor) circulated throu'gh the jacketspace in a manner which is "now'we'll known.

Withthefparts in the positions shown, a valve 15 for liquid oxidizer is open, the oxidizer being delivered from a main oxidizer line 16 to an annular chamber'17 at the upstream"end :of the evaporator portion 11, after which it'is'passed through holes 23 'into the portion 11where itis mixedwith' and evaporated by the combustion of a small portion of the oxidizer, passed through holes'24, and of a portion of theliquid' fuel delivered along a pipe line' 18' from an auxiliary fuel valve 19 supplied from a mainfuel pipe line 20. The rest of the fuel from the main pipe line'20 is'passed by a main fuel"va1ve'21 to the burner 12:by way of a pipe line 22.

Closure of a main switch energizes thewinding 26 of a'solenoid valve, thus opening this against'a return sptingto'enable the valve to pass high-pressure fl'uid from apipeline 27. Someof the high-pressu'refluid passed by the solenoid'valve travels along a pipe line 28*and reacts ona piston 29 of the' oxidizer valve to hold'this open against its return spring, While abianch line 30flfr'on the' pipe line 28 deliversthepressure to' a piston 3'1'of the auxiliary fuelvalve, therebyiholdingthe latter o en against its springbias. Tlie'high-preSsI'ire fluid is also "delive'redhlong" a pipe line"'32 to a control valve '33 and thence to actuatea' piston '34 oftlie main fnervalve and'hold' the latter open:

The pressure in the evaporator portion. along a pipe line to a piston 36in the controhvalve 33 "to move it to the position shown against areturn bias when the evaporator portion is functioning sufiiciently to provide the necessary pressure, and it is'only'then that the main fuel valve piston 34becomes actuated by the fluid pressure in the pipe line 37 and moved to the position shown-i. e., the burner12'will not be supplied'with fueiuntil a predetermined A in the evaporator portion 11.' Movement of the control valve inthis way disconnects a vent38fromthe pipe 1ine'37l Thus, with thepar'tsin 'the'positi'onshowng therocket motor is operating as long as fuel and oxidizer are being delivered to the pipe lines 20 and 16 respectively. 40 represents an igniter in the evaporator portion which is supplied by a conductor from a spark generator 41, the primary circuit for which is fed from a conductor 42 when the main switch 25 is closed.

In the present instance the casing 14 and its jacket (not shown) for cooling fluid is enclosed by a fluid-tight jacket 44 having a supply line 45, the jacket 44 being sealed at its ends and elsewhere as necessary to the cooling jacket around the casing 14. As stated, the supply line 45 is fed from a source of pressure, such as a bottle 45a of nitrogen under pressure which is higher than that within the rocket motor during the operation of the rocket motor. Consequently, if the casing 14 and its surrounding cooling jacket should burn through, the communicating aperture between the interior" of the rocket motor and the space of the jacket 44 will allow the higherpressure fluid from the supply line 45 to pass into the interior of the rocket motor, thus preventing the flaming gases in the rocket motor from passing outwardly through the aperture and constraining them to move in their normal direction.

Figure 1 also discloses a means for cutting off the supply of the combustion ingredients to the rocket motor when a communicating aperture is established as aforesaid, this means being responsive to a fall in. the pressure of the fluid in the supply line 45. Thus, the latter is connected by a line 47 to a pressure-responsive switch 11" is applied pressure is being; generated 4? which is biased to the open position but is held closed (as shown) by the pressure in the supply line 45 when conditions are normal, its switch contacts 49 being in series with the control switch 25. However, when a communicating aperture as aforesaid is established, there will be an immediate fall in pressure in the supply line which will enable the pressure-responsive switch 48 to open its contacts 49, and, to make sure that the contacts 49 will remain open in these conditions, it is helpful to include in the supply line 45, upstream of the line 47, a constriction, as indicated at 50.

Thus, should the temperature within the rocket motor rise so high as to burn through the fluid-cooled casing 14, the circuit of the solenoid valve will be disconnected at the contacts 49 and the solenoid will be de-energized, thereby cutting ofl the valve-operating pressures; and, at the same time, it opens a vent 52 to allow the fluid pressure to escape from the pressure-responsive valves so that these can close under their spring pressures and prevent a further supply of the combustion ingredients to the rocket motor, the pressure on the main fuel valve piston 34 being vented at 38 by the control valve 33.

As an obvious alternative, as shown by Figure 2, the pressure-responsive switch 48a could be biased to a closed position in which it completes a circuit for the winding 54 of a relay. In normal operating conditions the pressure-responsive switch has its contacts 49a open, as shown, thus de-energizing the relay to a position in which a circuit is completed for the winding of the solenoid valve through its contacts 55, the latter contacts being in this instance in series with the switch 25. But on a communicating aperture being established between the interior of the jacket-cooled rocket casing 14 and the enclosing jacket 44, the relay becomes energized to open the circuit for the solenoid-actuated valve at the contacts 55 and to provide, for itself, a holding circuit at the contacts 56.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A device such as a rocket motor having a chamber in which combustion ingredients are burned, a fluid-tight jacket enclosing the exterior of said chamber, a pipe line connected to the interior of said jacket, the jacket forming with the chamber wall an annular chamber closed except for the connection of the pipe line thereto, means for supplying to said line fluid which is at a higher pressure than that obtaining in said chamber during operation of the device, and means for cutting off the supply of combustion ingredients to said chamber, said lastmentioned means being responsive to a fall in the pressure of the fluid in the interior of said jacket.

2. A device such as a rocket motor having a chamber in which combustion ingredients are burned, a fluid-tight jacket enclosing the exterior of said chamber, a pipe line connected to the interior of said jacket, the jacket forming with the chamber wall an annular chamber closed except for the connection of the pipe line thereto, means for supplying to said line fluid which is at a higher pressure than that obtaining in said chamber during operation of the device, said pipe line also in connection with a pressure-responsive switch, said switch arranged to control the circuit of a solenoid valve controlling a further supply of fluid pressure, and pressure-operated valves responsive to said further supply of fluid pressure for controlling the supply of combustion ingredients to said chamber.

3. A device, according to claim 2, and including a constriction in said pipe line disposed upstream of the connection of said line to the pressure-responsive switch.

4. A rocket motor having a chamber in which combustion ingredients are burned, a solenoid valve, fluidpressure valves controlling the supply of the combustion ingredients to said chamber, said fluid-pressure valves operable by a source of pressure controlled by the solenoid valve, a fluid-tight jacket surrounding the exterior of said chamber, a pipe line supplying fluid to the interior of said jacket from a source which is at a pressure higher than would obtain in said chamber during operation of the rocket motor, the jacket forming with the chamber wall an annular chamber closed except for connection of the pipe line thereto, a constriction in said pipe line, and a pressure-responsive switch connected to said pipe line between said constriction and the jacket space, said switch adapted to control the circuit of the solenoid valve.

References Cited in the file of this patent UNITED STATES PATENTS 

